The present invention relates to a device for aerating water, especially during purification of water and for waste water. The device includes a rigid, essentially planar support member, and a plate of elastomeric material, such as rubber or rubber-like synthetic material. The plate is disposed on the support member and is provided with fine slits for the release of air. The support member is provided with one or more connectors for supplying air between the support member and the plate. The rim of the plate is connected in an airtight manner to the support member.
With the heretofore known aerating devices of this type, the plate has the same thickness throughout. This fact, as well as the fact that for mechanical reasons the rim portion of the plate must be secured in places to the support member, result in a bulging of the plate under the effect of the internal pressure of the air. In particular, the plate generally bulges to such an extent that it assumes an approximately balloon shape.
This physically unavoidable bulging leads not only to an undesirably great expansion of the plate in the zenith portion of the bulge, but also results in a greater opening of the slits and a smaller water counterpressure at that location. Thus it is impossible to prevent the release of air in the zenith portion from being greater, with the size of the air bubbles also being larger.
It is therefore an object of the present invention to eliminate these drawbacks and to provide a reduced bulging of the plate and a more uniform release of air over the entire surface of the plate.